Electron-antineutrino spectrum from precision measurements of $^{144}$Pr-decay

Abstract

The $^{144}$Ce -- $^{144}$Pr electron antineutrino source is one of the most suitable radiochemical sources for experiments searching for the oscillations of active neutrinos to the light sterile state. In the current work the $\beta$-spectra of $^{144}\rm{Ce}$ -- ${^{144}\rm{Pr}}$ source have been measured by two types of $\beta$-spectrometers based on silicon Si(Li) detectors in order to determine the energy spectrum of electron anti-neutrino emitted in the $\beta$-decay of $\rm{^{144}Pr}$ nuclei. The nuclear shape factor of the ground state beta transition in ${^{144}\rm{Pr}}-{^{144}\rm{Nd}}$ has been obtained with high precision: $C(W) = 1 + (-0.0301 \pm 0.0007)W + (-0.101 \pm 0.006)W^{-1}$. The reduced cross section for the inverse beta decay reaction on hydrogen for the $\rm{{^{144}Pr}}$ electron anti-neutrino source has been defined as $\rm{(4.7344 \pm 0.0006_{stat} \pm 0.013_{syst}) \times 10^{-44}~cm^2 {decay}^{-1}}$ that provides sufficient sensitivity to search for a sterile neutrino with a mass of $m_4 \sim 1$~eV and a mixing angle $Sin^2(2\theta_{14}) \sim 0.005$ using standard disappearance method.